A post-mix beverage dispenser generally includes a cooling reservoir having an evaporator for constantly cooling potable water, as shown in U.S. Pat. No. 4,493,441 which is incorporated by reference. Since the evaporator for cooling potable water is disposed within the cooling reservoir, the cooling reservoir must be fixedly disposed in the interior of the post-mix beverage dispenser. Accordingly, potable water to be mixed is conveyed on the location of the post-mix beverage dispenser and is supplied directly to the cooling reservoir.
The above-discussed post-mix beverage dispenser has several disadvantages. First, a predetermined time must lapse after the potable water is supplied to the cooling reservoir before it is sufficiently cooled. Second, the cooling reservoir is open-type and is not sanitary. Finally, post-mix beverage dispenser cannot be easily connected to an external water supply for automatic refilling of the cooling reservoir.